If you're doing any professional video I'd suggest getting a real video camera. I get frustrated with my attempts at non professional video on a DSLR. Poor focus control, poor live controls, poor viewing screen, poor audio control and input. If you're a poor indie filmmaker, or a Photog who wants occasional video it is nice, otherwise I wouldn't bother.
Well you seem to forget that i also wanna shoot pictures.
Also, I don't really agree with you on certain points; tried 7D (latest firmware) + 5d2 (magic lantern 2.3 firmware) and i didn't notice any of those things you mention.
I also tried real video cameras such as Z7, it of course feels nice, but i always prefer the colors & the DOF on a DSLR.
The bottom line is that where conditions, type of footage required and ability to plan carefully are optimal it is going to be hard to replicate the sheer beauty of DSLR video footage on anything other than a really expensive camcorder.
The versatility and optimisation of a 'real' camcorder is simply not present on any DSLR (that I could afford).
Your post seems to imply that you think you can pull off the video that you require with a 5D2 and the accessories that you have. If that is the case, then it shoots great stills.
For me, if you ever want to shoot video of something fast moving the 5d2 is out. My focusing skills just aren't there.
So far, you have specified
1. a single device
2. to be used for stills and mostly interview video
So the relatively affordable options:
1. T4i - good compromise for video and stills, cash left for mics etc.
2. 7D - price has dropped, APS-C slightly safer for video depth of field, good build quality, focusing would be a challenge on anything moving during video.
3. 5D2 - best still images out of my options, most difficult to use for video (most likely to encounter a situation where it is simply not useable), great video quality under optimal conditions.
4. The best camcorder for the price that you want to pay that shoots good stills. My XF100 shoots rubbish stills, so I can't help you there.
At anything under $2000 you are not going to get, brilliant versatile video capabilities and top shelf still quality. And if you find it let me know. It still comes down to what will you do the most and what is most importnat that you get right.
From previous posts I am presuming you don't want to spend a bomb. What is the actual budget?